I suppose between the two, I would opt for a Sunset just because it's less of an imposition to be available to see it.  I am not a morning person.  That said, the rise and fall of the sun has never been too appealing to me in general.  I've seen some amazing photos, though, capturing both events but I'm never had a personal experience that captures that beauty.
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How old were you when you had your first romantic kiss? (And with whom?)